Many kinds of deadbolt assemblies are commercially available. Deadbolts are thrown and retracted by means of a key-operated cylinder which passes through a hub of the deadbolt assembly. Turning the key turns the hub, which causes a cam or actuator to throw or retract the bolt. Some deadbolts are operated by a single cylinder, wherein the deadbolt is actuated by a key from outside the door and by a turnpiece from inside the door. Other deadbolts are operated by a double cylinder, wherein the deadbolt is thrown or retracted by a key from both sides of the door.
Deadbolts are thrown and retracted into a doorpost through a metal plate called a strike. The distance between the strike and the center of the hub is called the backset. In the United States, standard backsets are generally 2.375 inches or 2.75 inches. The throw of the deadbolt varies from one lock to another, with the maximum generally being 1 inch.
Most deadbolts are fixed at one standard backset or another. However, deadbolts with an adjustable backset are known. For example, KWIKSET manufactures and sells a deadbolt with a helical screw body (for example, its 880 series). By turning the strike, one can change the backset from 2.375 to 2.75 inches, and vice versa. SCHLAGE manufactures a line of deadbolts (B160 Grade 3 deadbolts) wherein the hub can be slid from one end of an elliptical hole to another, thereby adjusting the backset from one standard size to another.
However, adjustable-backset deadbolts of the art suffer from a drawback of a relatively weak mechanical connection between the deadbolt and the hub end of the assembly. This makes adjustable-backset deadbolts generally unsuitable for high security installations. In addition, the spacing between mounting screws used to mount the key-operated cylinder to the deadbolt assembly are not standard in prior art adjustable-backset assemblies.
Generally, deadbolt assemblies are not particularly flexible when non standard applications are required. For example, when conventional deadbolt assemblies are mounted on bevel-mounted doors, the faceplates must be specially enlarged and specially aligned to match the particular application. Similarly, when conventional deadbolt assemblies are mounted on doors of non-standard thickness, special hardware must be used.